GTA IV cost $100 million to develop.
 

GTA IV, however, has already sold over 600,000 copies on the first day in the UK alone and analysts have predicted that the game could gross more than USD 400 million in its first week.

http://www.gamesindustry.biz/article...ever-developed

Considering how much it cost to develop, it's a good thing Rockstar Games is selling a ton of these games... :)

1:4 profit is not bad, there are worse investments;)

but it proves a quality game does sell